pmdomain: mediatek: Add support for MTK_SCPD_STRICT_BUS_PROTECTION cap

This adds support for MTK_SCPD_STRICT_BUS_PROTECTION capability. It is a
strict bus protection policy that requires the bus protection to be
disabled before accessing the bus.
This is required by the mt8365, for the MM power domain.
Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Signed-off-by: Fabien Parent <fparent@baylibre.com>
Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Tested-by: Alexandre Mergnat <amergnat@baylibre.com>
Link: https://lore.kernel.org/r/20230918093751.1188668-8-msp@baylibre.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/pmdomain/mediatek/mtk-pm-domains.c

@@ -262,9 +262,17 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
 	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_ISO_BIT);
 	regmap_set_bits(scpsys->base, pd->data->ctl_offs, PWR_RST_B_BIT);
 
-	ret = clk_bulk_prepare_enable(pd->num_subsys_clks, pd->subsys_clks);
-	if (ret)
-		goto err_pwr_ack;
+	/*
+	 * In few Mediatek platforms(e.g. MT6779), the bus protect policy is
+	 * stricter, which leads to bus protect release must be prior to bus
+	 * access.
+	 */
+	if (!MTK_SCPD_CAPS(pd, MTK_SCPD_STRICT_BUS_PROTECTION)) {
+		ret = clk_bulk_prepare_enable(pd->num_subsys_clks,
+					      pd->subsys_clks);
+		if (ret)
+			goto err_pwr_ack;
+	}
 
 	ret = scpsys_sram_enable(pd);
 	if (ret < 0)
@@ -274,12 +282,23 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
 	if (ret < 0)
 		goto err_disable_sram;
 
+	if (MTK_SCPD_CAPS(pd, MTK_SCPD_STRICT_BUS_PROTECTION)) {
+		ret = clk_bulk_prepare_enable(pd->num_subsys_clks,
+					      pd->subsys_clks);
+		if (ret)
+			goto err_enable_bus_protect;
+	}
+
 	return 0;
 
+err_enable_bus_protect:
+	scpsys_bus_protect_enable(pd);
 err_disable_sram:
 	scpsys_sram_disable(pd);
 err_disable_subsys_clks:
-	clk_bulk_disable_unprepare(pd->num_subsys_clks, pd->subsys_clks);
+	if (!MTK_SCPD_CAPS(pd, MTK_SCPD_STRICT_BUS_PROTECTION))
+		clk_bulk_disable_unprepare(pd->num_subsys_clks,
+					   pd->subsys_clks);
 err_pwr_ack:
 	clk_bulk_disable_unprepare(pd->num_clks, pd->clks);
 err_reg:

drivers/pmdomain/mediatek/mtk-pm-domains.h

@@ -12,6 +12,7 @@
 #define MTK_SCPD_ALWAYS_ON		BIT(5)
 #define MTK_SCPD_EXT_BUCK_ISO		BIT(6)
 #define MTK_SCPD_HAS_INFRA_NAO		BIT(7)
+#define MTK_SCPD_STRICT_BUS_PROTECTION	BIT(8)
 #define MTK_SCPD_CAPS(_scpd, _x)	((_scpd)->data->caps & (_x))
 
 #define SPM_VDE_PWR_CON			0x0210
@@ -107,7 +108,7 @@ struct scpsys_domain_data {
 	u32 sram_pdn_ack_bits;
 	int ext_buck_iso_offs;
 	u32 ext_buck_iso_mask;
-	u8 caps;
+	u16 caps;
 	const struct scpsys_bus_prot_data bp_cfg[SPM_MAX_BUS_PROT_DATA];
 	int pwr_sta_offs;
 	int pwr_sta2nd_offs;